Adjustable Capacity Gas Incinerator

ABSTRACT

An adjustable capacity gas incinerator includes a base portion defining a lower chamber through which combustion air can flow from outside the gas incinerator into the lower chamber. A combustion stack extending vertically upward from the base portion and having a wall defining a combustion chamber and a combustion gas exit opening through which products of combustion can exit the combustion chamber. The combustion stack includes a lower stack section and an upper stack section removably joined to the lower stack section and which is removable from the lower stack section to change a combustion capacity of the combustion chamber.

FIELD OF THE INVENTION

The present invention relates generally to gas incinerators, and moreparticularly, relating to a gas incinerator that completely combusts gaswithout visible flames at the outlet for the combustion gases and thathas a variable capacity that is adjustable according to combustiondemand.

BACKGROUND OF THE INVENTION

There are several factors that govern the gas flow rate capacity of agas incinerator and one of those is the height of the combustion stack.All other design features being identical, a taller combustion stack hashigher efficiency than a lower combustion stack. Within the oil and gasindustry, there are many areas where gas incineration is required. Twoof the most common are initial well flow backs and productionfacilities. Due to the potential for large fluctuation in gas flow ratesbetween these two activities, it is challenging to adequately serve bothimportant needs. It has been a customary practice for industry to rentlarge capacity incinerators for the initial flow backs and then removethose after a sufficient wellbore evaluation flow back period to makeroom for the purchase of many small incinerators for their productionfacilities. This is an expensive and time-consuming process.

Oil and gas wells initially flow at high rates and, after the initialflow period, there is a natural decline and reduction in flow rate fromthe wells prior to the production facility being commissioned. Anothercontributing factor is that many production facilities will havepipelines being constructed to transport gas away from the productionfacility, however, those pipelines often cannot accommodate the full gasflows. For these reasons incinerators are required for productionfacilities but for reduced capacities as compared to the initial wellcapacities.

Accordingly, there is a need for a single gas incinerator having acombustion capacity capable of handling an initial, high gas flow rateand, then once the gas flow rate declines, the combustion capacity canbe reduced to meet the lower gas flow rate, thereby eliminating the needto install a high capacity incinerator and then replace the highcapacity incinerator with smaller capacity incinerator.

SUMMARY OF THE INVENTION

The present specification describes a gas incinerator having acombustion capacity that can handle an initial, high flow gas rate and,then once the gas flow rate declines, the combustion capacity isadjustable to meet combustion demand of the declined gas flow rate.Combustion capacity is adjustable by providing a combustion stack havinga stack height that can be decreased to meet combustion demands.

The present gas incinerator would be set in the precise location wherethe smaller lower capacity incinerator would normally be set up. Oncethe wellbore evaluation period was completed the top portion of thecombustion stack would be removed and a smaller, but appropriate,capacity stack would remain to serve the requirements of the productionfacility. In other words, what was traditionally a temporary incineratorwould become the permanent incinerator, by removing the top portion.

This is an operational breakthrough in that industry significantlyreduces equipment handling and their overall lease size. Further,purchasing the bottom portion of the incinerator and renting the topportion is much more economical than current practice where a fullincinerator is rented and then replaced by purchasing a completelydifferent designed production incinerator. The removed tops would thenbe re-used on incinerator bottoms on other projects and the operationsimply repeats.

According, in general, in one aspect, a method for incinerating gas isprovided. The method comprising the steps of:

-   -   a. providing a gas incinerator that has a base portion defining        a lower chamber through which combustion air can flow from        outside the gas incinerator into the lower chamber, a combustion        stack extending vertically upward from the base portion and        having a wall defining a combustion chamber in communication        with the lower chamber at one end and a combustion gas exit        opening at its opposite end through which products of combustion        can exit the combustion chamber, and the combustion stack having        a lower stack section and an upper stack section removably        connected to the lower stack section by a bolt and flange        coupling;    -   b. injecting gas from a source of gas at a flow rate into the        combustion chamber and combusting the gas in the combustion        chamber; and    -   c. removing the upper stack section from the lower stack section        when the flow rate of the gas declines to a rate in which the        upper stack section is not required to maintain combustion of        the gas without the combustion occurring beyond the combustion        gas exit opening.

In general, in another aspect, a gas incinerator with a variablecombustion capacity is provided. The gas incinerator includes a baseportion defining a lower chamber through which combustion air can flowfrom outside the gas incinerator into the lower chamber. A combustionstack extending vertically upward from the base portion and having awall defining a combustion chamber and a combustion gas exit openingthrough which products of combustion can exit the combustion chamber.The combustion stack includes a lower stack section and an upper stacksection removably joined to the lower stack section and which isremovable from the lower stack section to change a combustion capacityof the combustion chamber.

There has thus been outlined, rather broadly some features of theinvention so that the detailed description thereof that follows may bebetter understood and so that the present contribution to the art may bebetter appreciated.

Numerous objects, features and advantages of the present invention willbe readily apparent to those of ordinary skill in the art upon a readingof the following detailed description of presently preferred, butnonetheless illustrative, embodiments of the present invention whentaken in conjunction with the accompanying drawings. The invention iscapable of other embodiments and of being practiced and carried out innumerous ways. Also, it is to be understood that the phraseology andterminology employed herein are for description and should not beregarded as limiting.

As such, those skilled in the art will appreciate that the conception,upon which this disclosure is based, may readily be utilized as a basisfor the designing of other structures, methods and systems for carryingout the several purposes of the present invention. It is important,therefore, that the claims be regarded as including such equivalentconstructions insofar as they do not depart from the spirit and scope ofthe present invention.

For a better understanding of the invention, its operating advantagesand the specific objects attained by its uses, reference should be hadto the accompanying drawings and descriptive matter in which there areillustrated embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings illustrate by way of example and are included toprovide further understanding of the invention for illustrativediscussion of the embodiments of the invention. No attempt is made toshow structural details of the embodiments in more detail than isnecessary for a fundamental understanding of the invention, thedescription taken with the drawings making apparent to those skilled inthe art how the several forms of the invention may be embodied inpractice. Identical reference numerals do not necessarily indicate anidentical structure. Rather, the same reference numeral may be used toindicate a similar feature of a feature with similar functionality Inthe drawings:

FIG. 1 is a diagrammatic perspective view of an adjustable capacity gasincinerator constructed in accordance with the principles of anembodiment of the present invention;

FIG. 2 is a diagrammatic front view of the gas incinerator of FIG. 1 inpartial cross-section;

FIG. 3 is an enlarged, diagrammatic view of a bolted flange connectionbetween two combustion stack sections;

FIG. 4 is a diagrammatic, partial perspective view of a lower combustionstack section shown with an upper combustion stack section removedtherefrom; and

FIG. 5 is a diagrammatic, partial cross-section view showing a liftinglug removably attached to a combustion stack section.

DETAILED DESCRIPTION OF THE INVENTION

With initial reference to FIGS. 1 through 2, there is representativelyillustrated a new gas incinerator 10 in accordance with an embodiment ofthe present invention. The incinerator 10 includes a base portion 12defined by a cylindrical side wall 14 that has a plurality of airopenings 16 spaced therearound. The base portion 12 defines a lowerchamber 18, which receives ambient air located outside the incineratorthrough openings 16. A combustion stack 20 extends vertically upwardfrom the base portion 12 and has a wall 22 that defines a combustionchamber 24 that is in direct communication with the lower chamber 18.The incinerator 10 includes a combustion system for combusting gasinjected into the combustion chamber, such as the combustion systemdescribed by U.S. Pat. No. 6,168,422, the entirety of which isincorporated herein by reference.

The combustion stack 20 is divided along its height into a lower stacksection 26 and an upper stack section 28. The upper stack section 28 isjoined to the lower stack section 26 to create a continuous combustionstack 20 with combustion chamber 24 extending the height of thecombustion stack. The upper stack section 28 and the lower stack sectionare removably coupled together by a bolted flange connection 30. Theupper stack section 28 can be removed from the lower stack section 26 tochange the height of the combustion stack 20 and, thus, the capacity ofthe combustion chamber 24. The lengths or heights of the lower stacksection 26 and the upper stack section 28 may be varied to meetcombustion requirements of an installation. For example, the upper andlower stack sections 28 and 26 may have the same or different heights(lengths).

Detail of the bolted flange connection 30 is shown in FIG. 3. The boltedflange connection 30 includes a first flange member 32 disposed around atop end 34 of the lower stack portion 26 and a second flange member 36disposed around a bottom end 38 of the upper stack portion 28. Theflange members 32 and 36 are supported by a plurality of gussets 40. Theflange members 32 and 36 are connected by a plurality of bolts 42 thatextend through cooperating holes formed through the flange members. Withreference to FIG. 4, there is shown a partial view of the combustionstack 20 with the upper stack section 28 removed from the lower stacksection 26.

The mating flanges 32 and 36 on the upper and lower stack sections 28and 26 serve an additional purpose. The cylindrical stack is designedwith a wall thickness that requires mechanical strengthening in to betransported and set up. Without added mechanical strength theincinerator's steel walls might experience a deformation or bucklingduring these activities. The flanges add strength to mitigate this andthe mechanical qualities of the flange have been modeled appropriatelyto provide sufficient mechanical integrity.

The incinerator 10 also includes lifting lugs 44 for lifting andpositioning the incinerator and stack sections and, particularly, forlifting and positioning the upper stack section 28 on the lower stacksection 26. Turning to FIG. 5, each lifting lug 44 is removably attachedto the sidewall 22 of the stack section 26, 28 by a bolt 46 that isthreaded through front and back plates 48 and 50 welded to oppositesides of the sidewall 22.

In operation, the incinerator 10 is initially configured with thecombustion stack 20 having the upper stack section 28 secured to thelower stack portion 26 to provide a combustion chamber 24 having a firstcombustion capacity according an initial flow rate of a source gas 50that is to be burned. The height of the combustion stack 20 is such thatcombustion of the source gas 50 mixed with air 52 is entirely containedwithin the combustion chamber so that no flames exit the combustion gasexit located at the top end of the stack. Once the initial flow rate ofthe source gas 50 declines to a rate that combustion can be supportedentirely within the lower stack section 26 alone, the upper stacksection 28 is disconnected from the lower stack section and removed,thereby changing the combustion capacity of the combustion chamber 24.

An embodiment of the present invention has been described. Nevertheless,it will be understood that various modifications may be made withoutdeparting from the spirit and scope of the invention. Accordingly, otherembodiments are within the scope of the following claims. For example,while the description made herein describes the combustion stackcomprised of two sections, the lower section 26 and the upper section28, the combustion stack could be comprised of more than two sections toallow for finer combustion capacity adjustments.

What is claimed is:
 1. A method for incinerating gas comprising thesteps of: providing a gas incinerator that has a base portion defining alower chamber through which combustion air can flow from outside the gasincinerator into said lower chamber, a combustion stack extendingvertically upward from said base portion and having a wall defining acombustion chamber in communication with said lower chamber at one endand a combustion gas exit opening at its opposite end through whichproducts of combustion can exit said combustion chamber, and saidcombustion stack having a lower stack section and an upper stack sectionremovably connected to said lower stack section by a bolt and flangecoupling; injecting gas from a source of gas at a flow rate into saidcombustion chamber and combusting said gas in said combustion chamber;and removing said upper stack section from said lower stack section whensaid flow rate of said gas declines to a rate in which said upper stacksection is not required to maintain combustion of said gas without saidcombustion occurring beyond said combustion gas exit opening.
 2. A gasincinerator comprising: a base portion defining a lower chamber throughwhich combustion air can flow from outside the gas incinerator into saidlower chamber; a combustion stack extending vertically upward from saidbase portion and having a wall defining a combustion chamber and acombustion gas exit opening through which products of combustion canexit said combustion chamber; and wherein said combustion stack includesa lower stack section and an upper stack section removably joined tosaid lower stack section and which is removable from said lower stacksection to change a combustion capacity of said combustion chamber. 3.The gas incinerator of claim 2, wherein said lower stack section andsaid upper stack section are removably joined together by a boltedflange coupling.
 4. The gas incinerator of claim 3, wherein said boltedflange coupling includes a first flange member extending around saidwall of said lower stack section and a second flange member extendingaround said wall of said upper stack section.
 5. The gas incinerator ofclaim 3, wherein said first flange member reinforces said wall of saidlower stack section and wherein said second flange member reinforcessaid wall of said upper stack section.
 6. The gas incinerator of claim2, further comprising one or more lifting lugs disposed on said upperstack section.
 7. The gas incinerator of claim 6, wherein said one ormore lifting lugs are removably connected to said upper stack section.